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c# - 单击行时将动态值传递给事件处理程序

问题描述

请看下面的代码：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:App1"
             x:Class="App1.MainPage">

    <ContentPage.BindingContext>
        <local:PersonViewModel />
    </ContentPage.BindingContext>

    <StackLayout>
        <ListView x:Name="listView" ItemsSource="{Binding People}">
            <ListView.Header>
                <Grid>
                    <Grid.BindingContext>
                        <local:PersonViewModel />
                    </Grid.BindingContext>


                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*" />
                        <ColumnDefinition Width="*"  />
                        <ColumnDefinition Width="*"  />
                        <ColumnDefinition Width="*"  />
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto" />
                    </Grid.RowDefinitions>

                    <Label Grid.Column="1" Text="Id" />
                    <Label Grid.Column="2" Text="First Name" />
                    <Label Grid.Column="3" Text="Surname" />
                    <Label Grid.Column="4" Text="Date Of Birth" />
                </Grid>
            </ListView.Header>

        <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <Grid>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition Width="*"  />
                                <ColumnDefinition Width="*"  />
                                <ColumnDefinition Width="*"  />
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto" />
                            </Grid.RowDefinitions>
                            <Label Grid.Column="1" Text="{Binding Id}" />
                            <Label Grid.Column="2" Text="{Binding FirstName}" />
                            <Label Grid.Column="3" Text="{Binding Surname}" />
                            <Label Grid.Column="4" Text="{Binding Age}" />
                        </Grid>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </StackLayout>
</ContentPage>

和下面的视图模型：

public class PersonViewModel
    {
        private ObservableCollection<Person> _people = new ObservableCollection<Person>();

        public ObservableCollection<Person> People
        {
            get { return _people; }
        }

        public PersonViewModel()
        {
            _people.Add(new Person { Id = Guid.NewGuid().ToString(), Age = 36, FirstName = "Andrew", Surname = "Smith" });
            _people.Add(new Person { Id = Guid.NewGuid().ToString(), Age = 65, FirstName = "David", Surname = "White" });
            _people.Add(new Person { Id = Guid.NewGuid().ToString(), Age = 39, FirstName = "Bert", Surname = "Edwards" });
        }
    }

它按预期工作，即网格被添加到页面中。如果用户点击其中一行；我希望将该行的 ID 传递给事件处理程序。我该怎么做呢。我花了过去三个小时研究这个，但我还没有找到答案。我发现的最接近的是：https ://forums.xamarin.com/discussion/23002/how-do-you-detect-a-grid-click-tap 。但是，在这种情况下，传递的是静态值而不是动态值。

标签： c#xamarin

解决方案

我假设您想要对象的 ID，而不是行（因为这不相关恕我直言）

所以，Listview 有一个 ItemTapped 事件：

<ListView x:Name="listView" 
        ItemTapped="TappedListView"
        ItemsSource="{Binding People}">

而且，在您的 Page.xaml.cs

private void TappedListView(object sender, ItemTappedEventArgs e)
{
     var yourItem = e.Item as Person;
         var id = yourItem.Id;
}

您可以在官方文档中阅读更多关于 Listview Interactivity 的信息

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